Since the discovery of ferrocene in 1951, a number of metallocenes have been prepared by tile combination of anions having the cyclopentadienyl structure with various transition metals. The term "cyclopentadienyl structure" as used herein refers to the following structure. ##STR2## Such "cyclopentadienyl structure" can be formed by addition of various metal alkyls to cyclopentadiene and "cyclopentadiene-type" compounds.
The term "cyclopentadiene-type compound" as used herein refers to compounds containing the cyclopentadienyl structure. Examples of cyclopentadiene-type compounds include unsubstituted cyclopentadiene, unsubstituted indene, unsubstituted tetrahydroindene, unsubstituted fluorene, and substituted varieties of such compounds.
Many of the cyclopentadiene-type metallocenes have been found useful in catalyst systems for the polymerization of olefins. It has been noted in the art that variations in the chemical structure of such cyclopentadienyl-type metallocenes can have significant effects upon the suitability of the metallocene as a polymerization catalyst. For example, the size and substitutions on cyclopentadienyl-type ligands has been found to affect the activity of the catalyst, the stereoselectivity of the catalyst, the stability of the catalyst, and other properties of the resulting polymer; however, the effects of various substituents is still largely an empirical matter, that is, experiments must be conducted in order to determine just what effect a particular variation will have upon a particular type of cyclopentadienyl-type metallocene. Some examples of some cyclopentadienyl-type metallocenes are disclosed in U.S. Pat. Nos. 4,530,914; 4,808,561; and 4,892,851, the disclosures of which are incorporated herein by reference.
While there are references in the prior art which have envisioned metallocenes, there is no known reference disclosing bridged metallocenes chemically bonded to an inorganic support which can be used in a heterogeneous system such as, for example, heterogeneous catalyst for olefin polymerization. It would be a contribution to the art if a bridged metallocene or ligand chemically bonded to an inorganic support is provided. It would also be a contribution to the art if a process for making or using the bridged metallocene or ligand chemically bonded to an inorganic support is developed.